As is known in the art, a toll road is a road on which an agency (either a private agency or a public agency) collects money from users who wish to drive vehicles on the road. Typically, users pay a toll at so-called toll booths located at toll plazas which are established at certain locations along the road. The tollbooths sometimes include a gate which prevents a vehicle from passing through the toll booth unless a toll is paid. Once the toll is paid, the gate is raised to allow the vehicle to pass. Thus, to pay the toll at the tollbooth, the driver typically slows down the vehicle (or stops the vehicle if the toll booth has a gate) at the tollbooth and either pays a person acting as a toll collector or deposits money in a collection bin which registers payment of the toll.
As is also known, there is a trend on toll roads to automate the collection of the toll. Some automated toll collection systems allow electronic payment of the toll. To allow such automated electronic toll payment, users who wish to electronically pay the toll place a transponder in their vehicle. The vehicle transponder communicates with one or more reader systems which are mounted at predetermined locations (typically at toll plazas) along the toll road. Such automated toll systems do not require any gates, barriers or any physical impediments and thus, they free traffic flow on the highway. With this technique, tolling can be accurately and reliably conducted substantially at highway speeds (i.e. vehicles having transponders mounted therein need not slow down significantly or even at all for the toll to be collected).